Benchmark for mmap n KConfigBackEnd, was Bug #72586

Dirk Mueller mueller at
Mon Jan 19 14:03:52 GMT 2004

On Friday 16 January 2004 23:38, Dr. Juergen Pfennig wrote:

> I did some benchmarks and unfortunatately they show no effect of using
> mmap or not (even as an ex-particle physicist I don't see a peek - I should
> probably show it to my ancient professor who saw the peeks he wanted in
> almost every data set).

Well, in theory mmap avoids a memcopy, with the multi-hundred or MB/s even 
not-so-current machines can do, its normal that you don't see an effect on 
files 16k with such a low-resolution timer. 

There are files > 16k btw. kmailrc is a good example :)

> Is mmap() good for anything? Yes it is, if you do random walks through a
> file or if you skip portions while reading. 

Thats true. since we read the memory only once, mmap's effect is very limited. 

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